Originally Posted by chucklesR
I can understand water leaking around a chain plate's cover and corroding the top couple of inches of my cap plate (teak) and bulwark (4-6 inches high in that area - and that's before it gets to the 'hull' or the deck level.
How is would continue down the encapsulated - which I take to mean solid fiberglass and resin wrapped plate and then delaminate of cause movement enough to crack gell coat - I'm thinking that's rocket science and only a grinder can tell.
Unfortunately, but the time I have it ground out to see if there's a problem, well it will need to be replaced won't it.
The plate is not totally encapsulated. It protrudes where the rigging attaches. Stainless expands and contracts at a different rate than fiberglass. There is not a way to permanently seal this with fiberglass. Same issue occurs with rudderposts made of stainless inside fiberglass rudders - they all get wet eventually.
In my opinion that is the worst way to attach chainplates - at least for whoever owns the boat after a few decades.